U.S. patent number 7,686,074 [Application Number 12/033,819] was granted by the patent office on 2010-03-30 for apparatus and method for active circuit protection of downhole electrical submersible pump monitoring gauges.
This patent grant is currently assigned to Baker Hughes Incorporated. Invention is credited to Gordon Besser, James E. Layton, Robert H. McCoy, Larry J. Parmeter.
United States Patent |
7,686,074 |
McCoy , et al. |
March 30, 2010 |
Apparatus and method for active circuit protection of downhole
electrical submersible pump monitoring gauges
Abstract
Embodiments of the present invention beneficially provide
circuits and methods which isolate downhole electronics of a well
pump assembly from a power surge. The pump assembly includes a
motor and a housing, including head, base, and manifold plate. The
head has a hollow interior and a shoulder. The head is mounted to
the motor so that, in operation, oil from the motor fills the
interior of the head. The base has an outside diameter to fit
snugly inside the head. The manifold plate is located between an
upper end of the base and the shoulder of the head so that the axis
of the manifold plate is perpendicular to the axis of housing. A
gauge circuit and an isolation circuit are mounted to the manifold
plate. The isolation circuit includes active semiconductor elements
to detect excessive voltage and to protect the gauge circuit from
the excessive voltage.
Inventors: |
McCoy; Robert H. (Talala,
OK), Layton; James E. (Chelsea, OK), Parmeter; Larry
J. (Broken Arrow, OK), Besser; Gordon (Claremore,
OK) |
Assignee: |
Baker Hughes Incorporated
(Houston, TX)
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Family
ID: |
39705656 |
Appl.
No.: |
12/033,819 |
Filed: |
February 19, 2008 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20080196887 A1 |
Aug 21, 2008 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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60902313 |
Feb 20, 2007 |
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Current U.S.
Class: |
166/66.4;
417/44.11; 417/423.3; 361/33; 166/68; 166/105 |
Current CPC
Class: |
E21B
43/128 (20130101); F04D 15/0077 (20130101); F04D
13/10 (20130101) |
Current International
Class: |
E21B
4/04 (20060101); E21B 43/00 (20060101); F04B
49/06 (20060101); H02H 7/09 (20060101) |
Field of
Search: |
;166/105,66.4,68
;417/423.3,423.7,44.1,44.11 ;361/30,31,33 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Thompson; Kenneth
Attorney, Agent or Firm: Bracewell & Giuliani LLP
Parent Case Text
RELATED APPLICATIONS
This application claims priority to U.S. Provisional Patent
Application No. 60/902,313, titled System and Method for Active
Circuit Protection of Downhole Electrical Submersible Pump
Monitoring Gauges, filed on Feb. 20, 2007.
Claims
We claim:
1. A well pump assembly, the pump assembly comprising: a motor; a
housing mounted to the motor; a gauge circuit located in the
housing, the gauge circuit being positioned to monitor at least one
physical parameter of an environment of the motor; and an isolation
circuit located within the housing and being coupled to the motor
and the gauge circuit, the isolation circuit comprising
semiconductor elements including circuitry being positioned to
detect a high voltage event and to protect the gauge circuit from
the high voltage event.
2. A pump assembly of claim 1, wherein the isolation circuit
comprises a plurality of isolated gate bi-polar transistors.
3. A pump assembly of claim 1, wherein the gauge circuit includes a
regulator being positioned to regulate power supplied from the
isolation circuit, the regulator being one or more of the
following: a switching regulator; a constant current regulator; and
a shunt regulator.
4. A pump assembly of claim 1, wherein the housing comprises: a
circular manifold plate having a seal on an outer diameter of the
manifold plate that seals to an inner surface of the housing, the
manifold plate further comprising: an upper surface, wherein the
isolation circuit is mounted to the upper surface, a lower surface,
wherein the gauge circuit is attached to the lower surface, and at
least one communication port extending between the upper and lower
surfaces.
5. A pump assembly of claim 1, wherein the gauge circuit includes a
PC board mounted perpendicular to an axis of the housing and an
accelerometer mounted in a plane perpendicular to the axis of the
housing.
6. A pump assembly of claim 1, wherein the gauge circuit includes a
gauge mounted inside the motor.
7. A pump assembly of claim 1, wherein the isolation circuit is
potted, thermally and electrically isolated, and located within
motor oil of the motor.
8. A pump assembly of claim 1, wherein the isolation circuit is
mounted within a gauge chamber of the housing with high voltage
feedthroughs.
9. A well pump assembly, comprising: a motor; a housing mounted to
the motor, the housing comprising: a head having a hollow interior
and a shoulder, the head being mounted to the motor so that, in
operation, oil from the motor fills the interior of the head, a
base having an outside diameter to fit snugly inside the head and
being attached to the head, and a manifold plate located between an
upper end of the base and the shoulder of the head so that the axis
of the manifold plate is perpendicular to the axis of housing, the
manifold plate having a lower surface and an upper surface; a gauge
circuit mounted to the lower surface of the manifold plate; and an
isolation circuit attached to the upper surface of the manifold
plate so that the isolation circuit is mounted inside the interior
of the head.
10. A pump assembly of claim 9, wherein the head has a first flange
being positioned to attach to the motor through a first bolt and
thread assembly, and wherein the base is attached to the head
through a second bolt and thread assembly located on a second
flange that extends around an outside diameter of the base.
11. A pump assembly of claim 9, further comprising: a seal ring
extended around an outside diameter of the manifold plate in order
to form a seal between an inside surface of the head and the
manifold plate.
12. A pump assembly of claim 9, wherein the isolation circuit is
potted, and thermally and electrically isolated.
13. A pump assembly of claim 9, wherein the isolation circuit
comprises a plurality of isolated gate bi-polar transistors.
14. A method of protecting a downhole gauge circuit of a well pump
assembly from excessive voltage, the method comprising: monitoring
a physical parameter of an environment of a motor assembly of a
well pump assembly via a gauge circuit; detecting an excessive
voltage on a neutral node of a three-phase power winding associated
with the motor assembly of the well pump assembly via active
semiconductor circuitry; and limiting electrical conduction via
active semiconductor circuitry to the gauge circuit of the well
pump assembly when excessive voltage is detected so that the gauge
circuit is protected from the excessive voltage.
15. A method of claim 14, wherein the step of limiting electrical
conduction via active semiconductor circuitry to the gauge circuit
involves disconnecting the power from the gauge circuit by forcing
an open circuit.
16. A method of claim 14, wherein the step of limiting electrical
conduction via active semiconductor circuitry to the gauge circuit
involves a regulator being positioned to regulate power supplied to
the gauge circuit, the regulator being one or more of the
following: a switching regulator; a constant current regulator; and
a shunt regulator.
17. A method of claim 14, wherein the active semiconductor
circuitry in the step of detecting an excessive voltage comprises a
plurality of isolated gate bi-polar transistors.
Description
BACKGROUND
1. Field of the Invention
This invention relates in general to downhole electrical
submersible pump ("ESP") electronics and, in particular, to
downhole ESP assemblies which utilize active semiconductor
circuitry to disconnect or regulate voltage to downhole electronics
for protection in the event of a power surge or grounded phase.
2. Description of the Prior Art
In conventional submersible pump installations, there may be a
system for monitoring various characteristics of the pump motor
environment, such as pressure, vibration, and temperature. Due to
the extreme conditions inside a well, it is important to be
continuously aware of these downhole operating characteristics. The
temperature is often 200.degree. F. or higher, while the voltage
and current being supplied is also at high levels.
There are various methods used to monitor downhole operating
characteristics. A surface unit typically monitors these and other
conditions via data sent from a downhole unit. For example, the
temperature of the motor provides an indication of the pump's
operating efficiency. As such, a temperature probe located within
the motor can provide an indication of whether or not the motor is
overheating, which may possibly lead to motor failure.
Submersible pump installations include a large horsepower electric
motor located in the well. The electric motor receives three-phase
AC power via a power cable extending from the surface with voltages
phase-to-phase being commonly 480 volts or more. The electric motor
drives a pump, of varying types, to pump well fluid to the surface.
The downhole gauge is used to monitor the downhole characteristics.
The gauge is in a housing connected to the bottom of the motor. The
gauge is coupled to the neutral node or Y point of the three-phase
power windings of the motor via an inductor of very large
inductance. The large inductor is used to filter out the motor AC
in order to prevent the AC from interfering with communication
signals transmitted between the downhole unit and surface unit. The
large inductors also work to protect the gauge from voltage surges
caused by varying phenomena, such as when one phase of the three
phase power becomes grounded, which results in a high voltage at
the three phase "Y" point of the motor.
This prior art approach has numerous disadvantages. For example,
the inductors are large and very expensive. Also, the high
inductance and capacitance values of the protection circuitry
restrict the communications bandwidth through the protection
circuitry. In addition, the inductors create a large leakage
current to ground as the output is typically limited with a zener
diode, which can cause corrosion in cases of higher voltages.
SUMMARY OF THE INVENTION
In view of the foregoing, embodiments of the present invention
beneficially provide circuits and methods which isolate downhole
electronics in the event of a power surge on the system.
Embodiments of the circuitry and methods of the present invention
advantageously provide isolation circuitry consisting of
semiconductor components mounted inside a housing located downhole
in an electrical submersible pump assembly which includes, for
example, a pump, motor, and gauge component. The isolation circuit
is coupled to a gauge processor which measures and tests various
downhole characteristics such as temperature, pressure, and
vibrations. In the event of a power surge on the system, the
isolation circuit will cease or limit electrical conduction,
thereby protecting the sensitive gauge electronics. As such, the
isolation circuitry of the present invention replaces the large
expensive chokes utilized in the prior art.
Embodiments of the present invention also provide a gauge circuit
which utilizes a switching regulator or constant current as an
internal control circuit for stabilizing the voltage and current of
the gauge circuit. There can be multiple sensors in the downhole
housing, including for example, a vibration sensor mounted within
the downhole housing on an axis perpendicular to the axis of the
downhole housing.
Embodiments of the present invention provide a well pump assembly.
The pump assembly includes a motor and a housing, including a head,
a base, and a manifold plate. The head has a hollow interior and a
shoulder. The head is mounted to the motor so that, in operation,
oil from the motor fills the interior of the head. The base has an
outside diameter to fit snugly inside the head. The manifold plate
is located between an upper end of the base and the shoulder of the
head so that the axis of the manifold plate is perpendicular to the
axis of housing. A gauge circuit is mounted to the lower surface of
the manifold plate. Mounting the gauge circuit to the manifold
plate, which is perpendicular to the axis of housing, allows, for
example, vibration sensors advantageously to detect vibrations in
the plane perpendicular to the axis of housing. In addition, an
isolation circuit is attached to the upper surface of the manifold
plate so that the isolation circuit is mounted inside the interior
of the head, and the manifold plate separates the isolation circuit
from the gauge circuit. The isolation circuit includes active
semiconductor elements to detect excessive voltage and to protect
the gauge circuit from the excessive voltage.
In view of the foregoing, the present invention provides isolation
circuitry and methods to protect sensitive downhole electronics in
an electrical submersible pump assembly by utilizing semiconductor
technology to provide a more compact, faster, cheaper, and
efficient pump assembly.
BRIEF DESCRIPTION OF THE DRAWINGS
Some of the features and benefits of the present invention having
been stated, others will become apparent as the description
proceeds when taken in conjunction with the accompanying drawings,
in which:
FIG. 1 is a block diagram of an electrical submersible pump
assembly in accordance with the prior art;
FIGS. 2 and 2A are a block diagram and a partial sectional side
view, respectively, of a downhole system according to an exemplary
embodiment of the present invention;
FIG. 3A is a circuit schematic of an isolation circuit according to
an exemplary embodiment of the present invention;
FIG. 3B is another circuit schematic of an isolation circuit
according to an exemplary embodiment of the present invention;
FIG. 4 is a sectional view of a downhole housing according to an
embodiment of the present invention;
FIG. 5 is a sectional view of a manifold plate according to an
embodiment of the present invention; and
FIG. 6 is a circuit schematic of a gauge processor according to an
embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The present invention will now be described more fully hereinafter
with reference to the accompanying drawings in which embodiments of
the invention are shown. This invention may, however, be embodied
in many different forms and should not be construed as limited to
the illustrated embodiments set forth herein; rather, these
embodiments are provided so that this disclosure will be thorough
and complete, and will fully convey the scope of the invention to
those skilled in the art. Like numbers refer to like elements
throughout.
Referring to FIG. 1, an exemplary embodiment of a prior art
electrical submersible pump installation is illustrated. A pump
motor assembly 10 is connected to a three-phase power source (not
shown) by means of three conductors 12 located inside power cable
14. Power cable 14 extends downhole from the surface to pump motor
assembly 10. The entire submersible pump installation of FIG. 1 is
located downhole inside a standard well casing. Motor assembly 10
is symbolically shown by a three-phase power AC winding 16, which
is Y connected and has a neutral, ungrounded node 18.
A ground return path downhole sensing unit 20 is coupled to neutral
node 18 of AC windings 16. Downhole sensing unit 20 contains
measurement circuitry which measures various downhole
characteristics and transmits them to the surface unit via power
cable 14. Coupled between neutral node 18 and sensing unit 20 is a
large inductor 22. Large inductor 22 filters out the AC power in
order to prevent interruption of the communication signals
transmitted between sensing unit 20 and the surface unit (not
shown). In addition, the large inductor 22 protects the sensing
unit 20 when a grounded phase creates a high voltage at the neutral
node. Power from the power source (not shown) located at the
surface is transmitted downhole via power cable 14. Power cable 14
is also be used as a communication means between sensing unit 20
and the surface unit (not shown), which allows the transfer of data
relating to downhole conditions.
The prior art method of FIG. 1 is disadvantageous because the
inductor (inductor 22) is large and very expensive, restricts the
communications bandwidth through the protection circuitry, and can
create a source of corrosion. Accordingly, Applicants realize the
need to overcome these disadvantages by utilizing active
semiconductor circuit components in accordance with the embodiments
of the present invention which will now be described.
Referring to FIG. 2 and FIG. 2A, an exemplary embodiment of the
present invention is illustrated. A pump 15 motor assembly 10 is
connected to a three-phase power source (not shown) by means of
three conductors 12 located inside power cable 14 which extend
downhole 17 from the surface 13. The entire submersible pump 15
installation of FIG. 2A is located downhole 17 inside a standard
well casing 19. Motor assembly 10 in FIG. 2 is symbolically shown
by a three-phase power AC winding 16, which is Y connected and has
a neutral, ungrounded node 18.
A housing 24 is attached to the lower end of pump motor assembly
10. Housing 24 contains an isolation circuit 26, which is
electrically coupled to neutral node 18 via conductor 23a.
Isolation circuit 26 is also electrically coupled to a grounded
gauge processor 28 (FIG. 6) via conductor 23b in order to transfer
data regarding the downhole conditions, such as, for example,
temperature and pressure. In operation, gauge processor 28
transmits the digital data back to the surface via a current loop,
orthogonal frequency-division multiplexing (OFDM), quadrature
phase-shift keying (QPSK), frequency-shift keying (FSK), or other
modulation scheme as understood by those skilled in the art. By
eliminating the large inductor 22 of the prior art, embodiments of
the present invention allow for higher frequency transmissions via
current modulation. As understood by those skilled in the art,
OFDM, QPSK, and FSK can transmit data to the surface electronics
much faster than is possible through a large isolation inductor. An
embodiment of the present invention employs FSK frequencies higher
than 2.0 KHz to be above the noise band of the ESP system and below
2 MHz to create enough power through the capacitance of the power
cable. The FSK can be through conductive signals or via progation
through the motor and power cable. Those skilled in the art will
recognize that other frequencies and modulations schemes can be
included. According to an embodiment of the present invention, in
the event of excessive voltage being fed from neutral node 18,
isolation circuit 26 will disconnect power from processor 28.
According to an alternate embodiment of the present invention, in
the event of excessive voltage being fed from neutral node 18,
isolation circuit 26 will limit or regulate current to the gauge
processor 28.
Isolation circuitry 26 can take the form of any variety of
semiconductor circuitries. As is well understood in the art,
semiconductors circuits are designed from materials which are
neither good conductors of electricity (such as copper) nor good
electrical insulators (such as rubber)--hence the term "semi"
conductors. The most common semiconductor materials are germanium
and silicon. According to design specifications, these materials
are then statically modified through a process known as "doping."
Doping is a process by which impurities are introduced into the
material, which in turn either creates an excess or lack of
electrons, thereby encouraging or discouraging electrical
conduction, respectively.
In addition to permanent modification through doping, the
electrical properties of semiconductors are often dynamically
modified by applying electric fields. The ability to control
conductivity in semiconductor material, both statically through
doping and dynamically through the application of electric fields,
has led to the development of transistors. A transistor is a
semiconductor device that uses a small amount of voltage or
electrical current to control a larger change in voltage or
current. Because of its fast response and accuracy, the transistor
may be used in a wide variety of digital and analog functions,
including switching and voltage regulation.
Moreover, semiconductors make it possible to miniaturize various
electronic components. Not only does miniaturization allow the
components take up less space, but also results in circuit
components which are faster and require less power. As such, in
order to take advantage of these characteristics, the present
invention employs semiconductor circuitry as a means for voltage
suppression and protection, thereby alleviating the disadvantages
associated with the large, less efficient, and more expensive
inductors.
Gauge processor 28 performs the logic, computational, and downhole
measuring functions of the embodiments of the present invention, as
understood by those skilled in the art. The circuitry of gauge
processor 28 can take various forms and an exemplary embodiment
will be discussed later in this disclosure. For example, the
circuitry (FIG. 6) of processor 28 could include a power system,
current transmitter, and various downhole sensors such as, for
example, a pressure transducer, vibration/accelerometer, or
temperature sensor. In operation, gauge processor 28 measures the
various characteristics of the downhole environment and transmits
them back to the surface via conductor 23b.
Referring to FIG. 3A, an exemplary embodiment of the circuitry for
isolation circuit 26 of the present invention is illustrated.
Again, the embodiments of the present invention are directed to the
use of semiconductor circuitry in protecting downhole electronics.
Therefore, the inventors consider this disclosure to encompass any
variety of such circuitry and designs. As such, those skilled in
the art will appreciate that the operation and design of the
present invention is not limited to this disclosure nor the
specific circuitry discussed herein, but is susceptible to various
changes without departing from the spirit and scope of the
invention.
In the exemplary circuit schematic of FIG. 3A, power is applied to
isolation circuitry 26 from the neutral Y point 18 via conductor
23a. If, during an electrical event, the Y point voltage becomes
excessive (generally due to a ground on one of the leads feeding
the motor), isolation circuitry 26 will open, thereby protecting
gauge circuitry 28. Isolation circuitry 26 includes a diode D1
coupled in series along conductor 23a at the input of isolation
circuitry 26. Diode D1 is utilized as a block when a megohm meter
is connected at the surface, which allows the downhole system to be
"megged" (or its insulation checked) in a reverse direction to 5000
VDC (or some other desired voltage). Also, a megohm reading in the
forward direction is possible in the event isolation circuitry 26
is open. Isolation circuitry 26 further includes a gate section 30
serving as the main isolation point for the circuit and a trip
section 32 which forces gate section 30 open when the voltage
applied to the circuit exceeds a specified threshold.
In the exemplary embodiment of FIG. 3A, gate section 30 includes
three insulated gate bi-polar transistors ("IGBT") Q1, Q2, and Q3
which are coupled in series to insure the voltage is divided
between them. In other embodiments of the present invention, the
gate section can comprise a different number of IGBT devices, as
understood by those skilled in the art. That is, the isolation
circuit comprises a plurality of isolated gate bi-polar
transistors, according to embodiments of the present invention. The
IGBT devices combine the simple gate drive characteristics of the
MOSFET with the high current and low saturation voltage capability
of bipolar transistors by combining an isolated gate for the
control input, and a bipolar power transistor as a switch, in a
single device.
In this example embodiment, each IGBT device (Q1, Q2, and Q3) is
rated at 1200 and the maximum voltage is 3000 VAC. Resistors R3,
R4, and R5 are coupled at the base of each IGBT Q1, Q2, and Q3 for
the purpose of biasing and power dissipation. Zener diodes D4, D5,
and D6 are coupled in parallel, in the reverse direction, with IGBT
Q1, Q2, and Q3, respectively, in order to protect IGBT Q1, Q2, and
Q3 from power surges being sent downhole from the circuit input.
Another diode D2 is coupled in series behind gate section 30
(between isolation circuit 26 and gauge processor 28) in order to
prevent power surges from being sent back into isolation circuitry
26 from gauge circuitry 28. More or different IGBT devices and
isolation circuitry can be utilized as protection from a higher
voltage, as understood by those skilled in the art.
Further referring to the exemplary embodiment of FIG. 3A, trip
section 32 includes zener diode D3 coupled in series with diode D1
in the reverse direction (cathode terminal of zener diode D3 is
coupled to cathode terminal of diode D1) in order to set the bias
voltage for isolation circuitry 26. Resistors R7 and R8 and
resistors R6 and R9 are coupled in series with zener diode D3 and
in parallel with transistor assembly Q4 respectively, for power
dissipation purposes. (Transistor assembly Q4 is a Darlington
transistor, which combines two bipolar transistors in tandem within
a single device so that the current amplified by the first is
amplified further by the second transistor.) The base of transistor
assembly Q4 is coupled in series behind resistors R7 and R8. The
collector terminal of transistor assembly Q4 is coupled to the base
of IGBTs Q1, Q2, and Q3, and acts as the primary "trip" point for
the circuitry. Another zener diode D7 is coupled between the
collector terminal of transistor assembly Q4 and ground in order to
regulate current flow into the collector terminal of transistor
assembly Q4. An alternate embodiment is to ground the anode of
zener diode D7, as illustrated in FIG. 3B, creating a limiter, or
regulator, to conductor 23b, as understood by those skilled in the
art.
In normal operation, zener diodes D3 does not conduct and the
resistor chain R3, R4, and R5 will form a divider which turns on
the gate section chain Q1, Q2, and Q3 using the voltage received
from the surface via conductor 23a. In the event the voltage
increases to the point where zener diode D3 begins to conduct, the
current flows through zener diode D3, thus causing transistor
assembly Q4 to activate. Once transistor assembly Q4 is activated,
gate section chain Q1, Q2, and Q3 is opened, or tripped, thereby
preventing any power flow to gauge circuitry 28 via conductor
23b.
In another exemplary embodiment, isolation circuitry 26 could also
include additional circuitry or alternative circuit designs. For
example, a diode could be coupled across the emitter and collector
terminals of transistor assembly Q4 in order to protect transistor
assembly Q4 from voltage surges entering the circuit via conductor
23a. Also, capacitors could be coupled at various locations in the
circuit in order to filter noise created by the diodes and
elsewhere on the system. In another exemplary embodiment, isolation
circuitry 26 may be potted with a high thermal conduction epoxy.
The epoxy isolates the circuitry from electrical arching, protects
the circuitry from particulates in the oil, and provides thermal
conduction for the resistors and components.
In yet another embodiment, the isolation circuitry can include a
small inductor before diode D1 to further eliminate spikes and ESP
motor noise. As understood by those skilled in the art, this
inductor may be much lower voltage due to the voltage drop across
the semiconductor circuitry.
Referring to FIG. 4, an exemplary embodiment of housing 24 of the
present invention is illustrated. Housing 24 includes a head 40,
base 42, and a manifold plate 44 which fits within the assemblies.
The head assembly 40 and base assembly 42, together with manifold
plate 44, form housing 24. Housing 24 is tubular shaped having a
hollow interior 34. Head 40 is attached to motor assembly 10 by way
of thread and bolt assembly 39 which is located on flange 41 that
extends around the outside diameter of head 40. Head 40 is attached
to base 42 through another bolt and thread assembly 46 located on a
flange 45 that extends around the outside diameter of base 42. Base
42 can be closed or other equipment can be attached to its lower
end. Conductor 23a extends through hollow interior 34 from motor
assembly 10 in order to feed power to isolation circuit 26 and
gauge processor 28.
Base 42 is of a diameter which allows it to fit snugly inside head
40. Extending around the inside hollow interior of head 40 is a
shoulder 43. As base 42 is moved into place inside the diameter of
head 40, manifold plate 44 rests between upper end 48 of base 42
and shoulder 43 of head 40. As such, the axis of manifold plate 44
is perpendicular to the axis of housing 24. In an alternative
embodiment, manifold plate 44 is mounted inside its own individual
housing (not shown). An o-ring 50 extends around the outside
diameter of manifold plate 44 in order to form a seal between the
inside surface of head 40 and manifold plate 44.
Referring to FIGS. 4 and 5, an exemplary embodiment of manifold
plate 44 of the present invention will now be described. Manifold
plate 44 forms the mounting for isolation circuit 26 and gauge
processor 28. Isolation circuit 26 is contained on a circuit board
on the upper surface 52 of manifold plate 44, while gauge processor
28 is contained on a circuit board on the lower surface 54 of
manifold plate 44. As such, once the housing 24 is assembled,
isolation circuit 26 will be mounted inside the motor oil of motor
assembly 10 on the upper surface 52 of manifold plate 44. Also, as
illustrated, isolation circuit 26 and gauge processor 28 are
mounted parallel to each other and perpendicular to the axis of
housing 24. In other embodiments of the present invention, the
isolation circuit 26 and gauge processor 28 may be mounted in other
orientations within the housing. A first o-ring 50 provides a
sealant to protect gauge processor 28 from oil and debris.
Likewise, a second o-ring 53 forms a seal between the inside
surface of head 40 and the outside surface of the base 42. The
pressure on the upper side of o-ring 50 will be at the motor oil
pressure, which is substantially equal to the hydrostatic pressure
in the well. The pressure on the lower side is at atmospheric
levels. As understood by those skilled in the art, nitrogen or an
inert gas can be used on the lower side to protect the electronics.
In addition, isolation circuit 26 is potted for protection from
particulates in the oil.
A pressure port 56 extends through manifold plate 44 from upper
surface 52 to lower surface 54 in order to allow gauge processor 28
access to the oil pressure for measurements and testing received
from pressure sensor 57 via wire 60. Pressure port 56 contains
threads which allow pressure sensor 57 to be screwed into port 56.
Pressure port 56 also contains a seal (not shown) in order to
prevent leakage of oil and debris. Sealed feedthroughs 58 are also
located through manifold plate 44 extending from upper surface 52
to lower surface 54 in order to allow power, as well as other data
(sent via wires), to be feed from conductor 23 a to isolation
circuit 26 and then on to gauge processor 28.
A vibration sensor 62 (e.g., accelerometer) can also be mounted to
the circuit board of gauge processor 28 in order to detect
vibrations. As discussed previously, manifold plate 44, as well as
the circuit boards of gauge processor 28 and isolation circuit 26,
is perpendicular to the axis of housing 24. As such, vibration
sensor 62 can detect vibrations in the plane perpendicular to the
axis of housing 24.
Referring to FIG. 6, an exemplary embodiment of the circuitry of
gauge processor 28 will now be described. Conductor 23b provides
voltage into input 64. A switching regulator 66 is coupled in
series to input 23b, which is used as an internal control circuit
that switches power transistors (such as MOSFETs) rapidly on and
off in order to stabilize and reduce the output voltage or current
supplied to the circuit to a selected level. Alternately, a
constant current or shunt regulator can be used instead of the
switching regulator 66, as understood by those skilled in the art.
A transmitter 68 is also coupled in series to input 64 and is used
to transmit measurements obtained by gauge processor 28 over the
system current loop. Coupled to transmitter 68 is an analog to
digital converter 70 ("A/D converter"), which is used to convert
the analog measurement data obtained from the sensors 74,76 of
gauge processor 28 from analog to digital form before they are
transmitted by transmitter 68. A programmable CPU/processor 72 is
coupled to transmitter 68 and A/D converter 70 in order to handle
all processing and circuit logic of gauge processor 28.
A number of sensors are coupled to A/D converter 70 in order to
obtain the necessary measurements of the downhole environment. As
illustrated in the exemplary embodiment of FIG. 6, one of the
pressure sensors 74,76 is used to measure the atmospheric pressure
surrounding gauge processor 28, while the other is used to measure
the oil pressure of the motor environment. Temperature sensor 78 is
coupled to A/D converter 70 and is used to obtain temperature
measurements of the motor oil. Lastly, a vibration sensor 80 is
coupled to A/D converter 70 in order to obtain vibration
measurements of the downhole environment. Each sensor transmits its
respective measurements as an analog signal, which must be
converted by A/D converter 70 before being sent to processor 72 and
then transmitted back to the surface via transmitter 68. Each
sensor is mounted onto the PC board of gauge processor 28, however,
in an alternative embodiment, any or all of the sensors can be
located elsewhere within the downhole system.
It is important to note that while embodiments of the present
invention have been described in the context of a fully functional
isolation circuit and related methods, those skilled in the art
will appreciate that the mechanism of the present invention and/or
aspects thereof are capable of being distributed in the form of a
computer readable medium of instructions in a variety of forms for
execution on a processor, processors, or the like, and that the
present invention applies equally regardless of the particular type
of signal bearing media used to actually carry out the
distribution. Examples of computer readable media include but are
not limited to: nonvolatile, hard-coded type media such as read
only memories (ROMs), CD-ROMs, and DVD-ROMs, or erasable,
electrically programmable read only memories (EEPROMs), recordable
type media such as floppy disks, hard disk drives, CD-R/RWs,
DVD-RAMs, DVD-R/RWs, DVD+R/RWs, flash drives, and other newer types
of memories, and transmission type media such as digital and analog
communication links. For example, such media can include both
operating instructions and/or instructions related to the circuitry
described above.
While this invention has been shown in only one of its forms, it
should be apparent to those skilled in the art that it is not so
limited but is susceptible to various changes without departing
from the spirit and scope of the invention. For example, various
circuitry, circuit components, and/or circuit designs can be
utilized to achieve the function of the gauge circuitry. As such,
those skilled in the art will appreciate that the operation and
design of the present invention is not limited to this disclosure
nor the specific circuitry discussed herein, but is susceptible to
various changes without departing from the spirit and scope of the
invention. In the drawings and specification, there have been
disclosed illustrative embodiments of the invention and, although
specific terms are employed, they are used in a generic and
descriptive sense only and not for the purpose of limitation.
* * * * *